1. Field of the Invention
The present invention relates to a two beam interference objective device, which can be attached to a microscope etc for use.
2. Description of Relate Art
Conventionally, a two beam interference objective device having an optical path dividing prism and a reference mirror is known.
For example, as shown in FIG. 6, has an objective 101, an optical path dividing prism 102 disposed between the objective 101 and a sample 104, and a reference mirror 103 disposed to one of light-paths divided by the optical path dividing prism 102.
In the two beam interference objective device, when illumination light is irradiated from upside of the objective 101 or left side of the optical path dividing prism 102, the light is divided into two light-paths by the optical path dividing prism 102, which are respectively irradiated to the reference mirror 103 and the sample 104. Then, the lights respectively reflected by the reference mirror 103 and the sample 104 inversely advance and are interfered by being superposed by the optical path dividing prism 102, which is transmitted to an observation equipment body through the objective 101.
At this time, when a distance L1 between the optical path dividing prism 102 and the sample 104 is equal to a distance L2 between the optical path dividing prism 102 and the reference mirror 103 (L1=L2), zero-order interference fringes is generated, and first-order, second-order, third-order interference fringes are generated as a difference between the distance L1 and the distance L2 increases by xcex/2 (xcex/2, xcex, 3xcex/2 . . . ) Here, xcex is a wavelength of the illumination light.
Accordingly, various physical quantities can be measured by analyzing the interference fringes.
Incidentally, some of the two beam interference objective device includes a tilting device for tilting the reference mirror for adjusting width and direction of the interference fringes.
Following two arrangements are known as the conventional tilting, which us disclosed in Publication of Japanese Utility Model Registration No. 2520950.
(1) An arrangement having: two adjusting knobs for tilting the reference mirror for adjusting width and direction of the interference fringes; and another adjusting knob for moving the reference mirror in an optical axis direction so that the reference mirror is located in a conjugate position relative to sample surface.
(2) An arrangement having two adjusting knobs for tilting the reference mirror centering the optical axis of the objective lens.
In the above, the xe2x80x9cconjugate positionxe2x80x9d of the reference mirror and the sample surface refers to a position where the reference mirror and the sample surface are located at the same distance relative to the optical path dividing prism.
However, following problems occur in the above-described arrangements.
According to the tilting device of the first arrangement, since an objective screw portion and a manipulative portion of the tilting device for adjusting interference fringes are fixed relative to a rotation direction around the objective lens optical axis, the adjusting knob has to be manipulated for generating the interference fringes after focusing on a image of the sample in order to set the reference mirror at a conjugate position relative to the sample and the other two adjusting knobs have to be manipulated for adjusting the width and the direction of the interference fringes, thereby complicating operation process to deteriorate work efficiency.
According to the tilting device of the second arrangement, though the conjugate position relative to the sample surface can be constantly maintained by pivotally moving the reference mirror around the optical axis of the objective lens, the two adjusting knobs have to be simultaneously manipulated for adjusting the width and the direction of the interference fringes, which requires both hands for simultaneous adjustment of the two adjusting knobs, resulting in bad operability.
An object of the present embodiment is to provide a two beam interference objective device capable of adjusting the width and direction of tile interference fringes by a single hand and improving operability and work efficiency for solving the above conventional problems.
A two beam interference objective device according to the present invention has an objective lens; an optical path dividing member provided between the objective lens and a sample; a reference mirror provided to first light-path divided by the optical path dividing member; and a tilting device for tilting the reference mirror to adjust width and direction of an interference fringes generated by a light reflected by the reference mirror and a light reflected by the sample disposed on second light-path divided by the optical path dividing member, the tilting device including: a width adjuster for pivotally moving the reference mirror centering an axis parallel to an optical axis of the objective lens while keeping an approximately constant distance from the optical axis of the objective lens to the reference mirror; and a direction adjuster for turning the reference mirror centering the second divided optical path, the width adjuster and the direction adjuster being manipulatable independently.
In the above, xe2x80x9capproximately constant distance from the optical axis of the objective lens to the reference mirrorxe2x80x9d means both the same distance from the optical axis of the objective lens to the reference mirror and slightly different distance from the optical axis of the objective lens to the reference mirror.
According to the above arrangement, since the width adjuster for adjusting the width of the interference fringes and the direction adjuster for adjusting the direction of the interference fringes are independently manipulatable, the width, for instance, of the interference fringes can be adjusted by manipulating the width adjuster with a single hand and, subsequently, the direction of the interference fringes can be adjusted by manipulating the direction adjuster. Accordingly, the width and the direction of the interference fringes can be adjusted with a single hand.
Further, when the width adjuster is manipulated, since the reference mirror is pivotally moved centering the axis parallel to the optical axis of the objective lens while keeping approximately constant distance from the optical axis of the objective lens to the reference mirror, the width of the interference fringes can be adjusted while fixing the zero-order band of the interference fringes at the center of a visual field. Further, when the direction adjuster is manipulated, since the reference mirror is turned centering the first divided optical path, the direction of the interference fringes can be adjusted while keeping the width of the interference fringes established by the width adjuster. Accordingly, operability and work efficiency can be improved.
In the present invention, the tilting device may include a first accommodating barrel connected to the objective lens and having the optical path dividing member thereinside, a second accommodating barrel connected to the first accommodating barrel and having the reference mirror thereinside, the width adjuster for pivotally moving the reference mirror centering the axis parallel to the optical axis of the objective lens while keeping the approximately constant distance from the optical axis of the objective lens to the reference mirror and the direction adjuster for turning the second accommodating barrel centering the second divided optical path.
According to the above arrangement, in addition to the aforesaid effects (single-hand operation and improvement in operability and work efficiency), since the direction of the interference fringes can be adjusted by rotating the second accommodating barrel having the reference mirror thereinside around the enter of the first divided optical path, minute direction adjustment of the interference fringes is possible.
Further, since the tilting device includes the first accommodating barrel having the optical path dividing member thereinside, the second accommodating barrel connected to the first accommodating barrel and having the reference mirror thereinside, the width adjuster for pivotally moving the reference mirror centering the axis parallel to the optical axis of the objective lens, and the direction adjuster for turning the second accommodating barrel centering the first divided optical path, the two beam interference objective device can be constructed just by connecting the first accommodating barrel of the tilting device to an ordinary objective lens.
In the present invention, the width adjuster may preferably includes a holder pivotablly supported in the second accommodating barrel centering the axis parallel to the optical axis of the objective lens and having the reference mirror, an adjusting knob screwed to the second accommodating barrel along the first divided optical path direction, and a movement converter for converting a movement of the adjusting knob in an axial direction thereof to a pivotal movement of the holder.
Accordingly, since the adjusting knob for adjusting the width of the interference fringes is screwed to the second accommodating barrel for adjusting the direction of the interference fringes along the first divided optical path direction, in other words, since the second accommodating barrel and the adjusting knob are closely disposed coaxially with the first divided optical path, interference fringes width adjustment can be rapidly switched to interference fringes direction adjustment, and vice versa.
The first accommodating barrel may preferably be rotatable centering the optical axis of the objective lens.
Accordingly, since manipulative position of the width adjuster and the direction adjuster can be turned centering the optical axis of the objective lens, the manipulative position can be shifted to an easier position for the observer to manipulate.
A shutter for opening and closing the first divided optical path may preferably be provided between the optical path dividing member and the reference mirror.
Accordingly, both of the interference fringes and bright-field can be observed with a single objective lens by opening and closing the first divided optical path by the shutter.